The present invention generally relates to drive sockets, and more specifically relates to an improved drive socket design for a hold and drive fastener.
U.S. Pat. No. 6,158,310 is hereby incorporated herein by reference in its entirety. FIG. 1 of the present application is FIG. 1 from the '310 patent. As shown in FIG. 1, the '310 patent discloses a drive system 20 in the form of a headed stud or fastener 22 having a drive head 24 and an elongate body 26. Between the drive head 24 and elongate body 26 is a transitional portion 28 which is generally conical. The elongate body 26 has a thread 34 formed thereon, and the transitional portion 28 includes alternating flutes 38 and lobes 40. Each of the flutes 38 and lobes 40 taper outward, progressing from a point 42 at which the drive head 24 meets the transitional portion 28 to the elongate portion 26, and each lobe 40 on the transitional portion 28 includes a thread 44. The drive head 24 also has alternating flutes 46 and lobes 48 which align with the alternating flutes 38 and lobes 40 on the transitional portion 28.
As shown in FIG. 1, also provided is a corresponding drive tool 30 which includes a drive socket 32 which is shaped and configured such that it corresponds with the profile of the drive head 24 and transitional portion 28 of the fastener 22. As such, the drive socket 32 also includes alternating flutes 50 and lobes 52. Specifically, when the drive socket 32 is engaged with the drive head 24 of the fastener 22 (i.e., for driving the fastener 22), portions 54 of the flutes 50 receive the lobes 40 of the transitional portion 28 of the fastener 22, and portions 56 of the flutes 50 receive the lobes 48 of the drive head 24 of the fastener 22. Likewise, portions 58 of the lobes 52 engage the flutes 38 of the transitional portion 28 of the fastener 22, and portions 60 of the lobes 52 engage the flutes 46 of the drive head 24 of the fastener 22. As shown in FIG. 1, portions 54 and 58 of the flutes 50 and lobes 52, respectively, of the drive socket 32, are disposed in a generally conical section 70 of the drive socket 32, and these portions 54, 58 taper (i.e., get wider) as the portions extend from a point 43 at which the conical section 70 begins in the drive socket 32 to the end 72 of the drive tool 30. In contrast, portions 56 and 60 of the flutes 50 and lobes 52, respectively, of the drive socket 32, remain a uniform width as they progress from an inside area 74 of the drive tool 30 to the point 43 at which the conical section 70 begins in the drive socket 32.
The drive socket 32 works to drive the fastener 22, but is configured such that it does not fully engage the flutes 38 of the transitional portion 28 of the fastener 22. For example, the threading forming may cause some threads to carry over into the flute portion of the conical portion of the fastener. As such, the lobes of the socket in the conical or transitional portion may not provide adequate clearance. Therefore, the socket design does not always achieve the target ultimate failure mode of torsional thread section failure.